Localization of metastable atom beams with optical standing waves: nanolithography at the heisenberg limit

The spatially dependent de-excitation of a beam of metastable argon atoms, traveling through an optical standing wave, produced a periodic array of localized metastable atoms with position and momentum spreads approaching the limit stated by the Heisenberg uncertainty principle. Silicon and silicon dioxide substrates placed in the path of the atom beam were patterned by the metastable atoms. The de-excitation of metastable atoms upon collision with the surface promoted the deposition of a carbonaceous film from a vapor-phase hydrocarbon precursor. The resulting patterns were imaged both directly and after chemical etching. Thus, quantum-mechanical steady-state atom distributions can be used for sub-0.1-micrometer lithography.     

Economically Important Leatherjackets of Grassland and Cereals: Biology, Impact and Control

Despite the large number of cranefly species only two have been convincingly associated with crop damage. The larvae of Tipula paludosa are commonly found as pests in both grassland and spring cereals whereas those of T. oleracea are only established as pests of winter cereals following crops of oilseed rape in the rotation. The latter, however, is probably the species involved in opportunistic situations involving various minor crops. These epidemiological contrasts are attributable to differences in the morphology and behaviour of the adults of the two species in relation to crop rotations. Larvae are sufficiently similar as to cause confusion in identification and this has hampered development of a clear picture of the ecology of the two species. Little is known about the distribution of T. oleracea larvae but T. paludosa larvae are largely regulated by climatic factors, especially rainfall, although the operation of these varies across the distribution range. Many natural enemies have been identified but a commercially viable control method using them has not yet been developed for either species. Control of T. paludosa is relatively easy using broad-spectrum insecticides but inconsistent kills have been observed with winter pesticide applications against T. oleracea. Determination of those fields requiring applications in advance of the damage remains the major problem, especially in grassland and winter cereals, to be resolved for the management of leatherjacket pests.     

Overlooked impacts and challenges of the new European discard ban

Discards are the portion of animal and plant material in the catch that is dumped back at sea. The Common Fisheries Policy plan proposed by the European Commission for 2014–2020 presents a controversial goal: to enforce the landing of fishing discards as a measure to encourage their reduction. This historical and political decision will shape the future of the fishing exploitation in European Seas. Discards generated by European fleets are not negligible, and its reduction is an ecological, socioeconomical and moral imperative. However, it must be achieved through the reduction in discards at source and the promotion of selective and non‐destructive gears. We argue it is doubtful that this discard ban will result in an effective reduction of discards. The proposed measure may, in fact, negatively affect ecosystems at all levels of biological hierarchy by disregarding the Ecosystem‐Based Approach to Fisheries and the Precautionary Principle. It could negatively impact several species by increasing fishing mortality, also commercial species if discards are not accounted in the total allowable catch. Communities preying on discards will likely be affected. The role discards currently play in the energy turnover of current ecosystems will be modified and should be fully evaluated. The landing of discards will likely generate new markets of fishmeal due to the growing demands for marine living resources. The ban will require substantial public investment to deal with technical problems on board and to control and enforce. Therefore, this measure should be only implemented after rigorous scientific and technical studies have been developed.     

Equine amnionitis and fetal loss: The case definition for an unrecognised cause of abortion in mares

A series of abortions occurred in mares in New South Wales during 2004 that involved similar and unusual findings on post mortem examination of aborted fetuses and fetal membranes. The term Equine Amnionitis and Fetal Loss (EAFL) was developed to describe the condition. This form of abortion had not been previously recognised in Australia. The pathology alone is not specific for EAFL and diagnosis requires demonstration of a combination of certain pathological and bacteriological features. The purpose of this paper is to describe patterns considered consistent with EAFL cases as a working case definition for use by veterinarians and veterinary pathologists in identifying future cases of EAFL. More detailed papers are in preparation to fully describe the epidemiological, histopathological, and microbiological aspects of EAFL.     

Species proportions by area in mixtures of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) and European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) dominate many of the European forest stands. Also, mixtures of European beech and Scots pine more or less occur over all European countries, but have been scarcely investigated. The area occupied by each species is of high relevance, especially for growth evaluation and comparison of different species in mixed and monospecific stands. Thus, we studied different methods to describe species proportions and their definition as proportion by area. 25 triplets consisting of mixed and monospecific stands were established across Europe ranging from Lithuania to Spain in northern to southern direction and from Bulgaria to Belgium in eastern to western direction. On stand level, the conclusive method for estimating the species proportion as a fraction of the stand area relates the observed density (tree number or basal area) to its potential. This stand-level estimation makes use of the potential from comparable neighboring monospecific stands or from maximum density lines derived from other data, e.g. forest inventories or permanent observations plots. At tree level, the fraction of the stand area occupied by a species can be derived from the proportions of their crown projection area or of their leaf area. The estimates of the potentials obtained from neighboring monospecific stands, especially in older stands, were poorer than those from the maximum density line depending on the Martonne aridity index. Therefore, the stand-level method in combination with the Martonne aridity index for potential densities can be highly recommended. The species’ proportions estimated with this method are best approximated by the proportions of the species’ leaf areas. In forest practice, the most commonly applied method is an ocular estimation of the proportions by crown projection area. Even though the proportions of pine were calculated here by measuring crown projection areas in the field, we found this method to underestimate the proportion by 25% compared to the stand-level approach.     

Can bioplastic or woodchip groundcover replace herbicides or plastic mulching for valuable broadleaf plantations in Mediterranean areas?

Weed control is fundamental in plantations of valuable broadleaved species. The most common weeding techniques are repeatedly applied herbicides and removable plastic mulching, both raising environmental concerns. We studied the performance of these techniques on a hybrid walnut plantation, compared with three biodegradable mulch alternatives: a prototype bioplastic film, a layer of composted woodchips and a layer of ramial chips. The durability and effect of the treatments on tree performance (survival, growth, physiological traits) and soil features (moisture and temperature) were evaluated over 4 years. Herbicide yielded the best results, while all the mulching treatments provided better results than controls for nearly all the variables. The performance of plastic and bioplastic films was similar, suggesting that the latter could replace plastic mulching. The performance of the two chip mulches was similar and slightly below that of the films, probably because of the excessive thickness of the former (13–14 cm). In summary, biodegradable mulches showed high effectiveness in controlling weeds and so could offer an alternative to herbicide application and plastic mulching when these are contra-indicated technically (accessibility, repeatability), economically (labour cost), legally or environmentally.     

氮素营养对冬小麦光合与光呼吸的调节

以冬小麦扬麦4号为材料,采取不同的施氮水平处理,研究氮素营养对冬小麦光合与光呼吸的调节.用氧电极测定RuBPOase活力.用~(14)C同位素测定RuBPCase活力,用红外线CO_2气体分析仪测定光合和光呼吸强度.结果表明:这些代表整体和酶学水平等几个不同层次的光合参数均随氮素水平的不同而有显著差异,且这些光合参数之间呈极显著的正相关.另外还观察到,光呼吸比光合作用对氮的反应敏感性更强.本文对氮与光呼吸的关系及光呼吸对碳氮代谢的调节机理进行了讨论.